There are three main trails used to reach the summit. The first is actually a continuation of the main trail to the summit of Grays Peak, which starts in Stevens Gulch. See the Grays Peak article for more information on accessing that trail.
A popular and challenging variation of this trail follows class-3 Kelso Ridge. This route splits from the Grays Peak trail two miles from the trailhead, climbs to the 12,400-foot saddle between Torreys and 13,164-foot Kelso Mountain, then follows the rugged ridge about a mile to the summit.
The third trail starts at Loveland Pass about 4½ miles to the northwest. To reach Loveland Pass, follow I-70 west from Denver 55 miles to where US Route 6 breaks off and heads south. Follow the meandering Route 6 approximately seven miles to the trailhead at Loveland Pass, at an elevation of 11,990 feet.
The steepest part of the trail actually begins right away with a half mile climb of 1,000 feet. The trail follows the Continental Divide gently taking the climber down into three saddles and up two more peaks, including Grizzly Peak (13,427 feet). The final saddle rests at approximately 12,600. From this saddle, it is a mile-long ascent of 1,800 feet to the final summit.
Once at the summit, many opt to continue on to Grays Peak, 0.75 miles away. The trail from Torreys Peak to Grays Peak dips down to a 13,707-foot saddle and then climbs back up to 14,270 feet.